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Blind Spot and the "Filling-in" phenomenon.

Did you know that your eyes have blind spots (and not just at the back of your head)? Each of your eyes contains an area that has no photoreceptors because it is occupied by the optic nerve. You may not have noticed these areas because they are on opposite sides of your visual field. However, this exercise is designed to isolate your blind spot and you will be amazed at the results.  

Instructions: Close your left eye and fixate your right eye on the cross in the first diagram. If your eye is about 12 inches (30 cm) away from the monitor, you should notice that the round dot disappears. This distance may vary according to the screen resolution you have set.

Close left eye and look at cross, what happens to dot?


You may be surprised to see that the dot is replaced, not by a black region, but rather blank white space. The brain simply "fills in" the most probable stimulus (in this case, a uniform white area) where there is none.

The following examples demonstrate the "filling-in" phenomenon in greater detail. Apply the same instructions as given above and you should notice the red markings each time are replaced by the most probable pattern that your brain is able to perceive. 

Close left eye and look at cross, what happens to "X"?





Close left eye and stare at cross, what happens to "X"?

Back to Optical Illusions

Other Illusions:
Blind Spots
Blink Effect
Chromatic Adaptation
Chromatic Adaptation
Color Blindness
Dither Dots
Fill Patterns
Opponent After-images
Optical Art
Shape Contrast
Simultaneous Contrast
Simultaneous Contrast
Value Contrast

Other fun stuff:
Free 3D Screensavers
Color Playground
Dimensions of Color
3D Color Puzzle

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